Morphological features of pollen, fruits, and seeds of Turkish Cistus species (Cistaceae)

Abstract

Pollen, fruit, and seed morphology of the Cistus species (Cistaceae) from Turkey were investigated by light microscopy (LM) and scanning electron microscopy (SEM) to describe their characteristics and to clarify the diagnostic importance of these properties for taxonomical purposes. The pollen grains are oblate-spheroidal, with the polar axis ranging from 32 to 55 μm, and the equatorial axis ranging from 34.25 to 57 μm. Microreticulate-rugulate, striato-reticulate, microechinate, and microreticulate with smooth supratectal elements were found on exine sculpturing. The fruits are ovoid, oblong-globose, or ovoid-globose, and their size ranges between 3–11.2 mm in length and 2.9–10.3 mm in width. Capsule surface patterns can be divided into three types, namely irregularly reticulate, striate, and reticulate-areolate. The hairs on the capsule show variation in type: pilose, bifurcate, and stellate. The seeds are polyhedral, ovoid, rhomboid, oblong, or tetrahedral, and their color varies between dark brown, reddish-brown, yellowish-brown, and black. Four seed coat ornamentation types were observed: reticulate-ruminate, reticulate-rugose, colliculate-ruminate, and alveolate-rugose. Cluster analysis and principal component analysis revealed that the pollen dimension, exine sculpturing, capsule size, capsule indumentum type, capsule surface pattern, seed color, and seed coat ornamentation are the most significant variables to differentiate the Cistus species studied.